*{
    margin: 0;
    padding: 0;
}

.banner{
    display: flex;
    justify-content: center;
}
.banner>div{
    display: flex;
    justify-content: center;
    background-color: #CCCCCC;
    width: 1920px;
    height: 400px;
}
.banner>div>div{
    display: flex;
    justify-content: center;
    background-image: url("../img/about_banner.jpg");
    width: 1500px;
    height: 400px;
}
